Garments such as tee shirts are decorated using multi printing head, screen printing machines. The number of heads correspond to the number of colors to be printed. U.S. Pat. No. 3,795,189 (Jaffa) and U.S. Pat. No. 5,031,527 (Eppinger) disclose examples of the type of machines used in printing garments. The garments are supported on a pallet, which in turn is supported, for registry with the printing head, on a pallet arm. The pallet is moved successively past the desired number of printing heads until the printing is complete. Different size garments require correspondingly different sized pallets. Usually pallets are of the same length but vary in width from a garment sleeve width to a large body width. This means that the pallets need to be removed from the pallet arms on a frequent basis.
The positioning of the pallet on its pallet arm needs to be precise and secure to ensure that registration with successive printing heads is maintained. Conventionally one means of removably securing pallets to pallet arms has been to use 2 or 3 counter sunk screws at each end of the pallet. This is quite adequate in terms of registration accuracy and retention of alignment but involves extensive labor time to fit a new set of pallets to a machine. A number of quick release mechanisms have been proposed. Some use a key and keyhole type arrangement where either the pallet or the pallet arm has a keyhole slot and the other has a complementary head that can be locked into the narrow part of the slot. Another quick release means relies on the use of a rail and complementary track arrangement with either the pallet or the pallet arm having a rail and the other having a channel track of complementary cross section to the rail and a securing means to lock the two relative to one another for registration relative to the length of the arm. In most of these devices several wing nuts or bolts need to be tightened to secure the aligned pallet to the pallet arm.
U.S. Pat. No. 4,031,825 (Jaffa) discloses a pallet which fits sleeve-like over the pallet arm and is held in place by springs in the side edges of the pallet arm. Even though the pallet appears to be simple it needs to be fabricated or machined extensively as does the pallet arm.
U.S. Pat. No. 5,592,877 in part discloses a pallet which can be installed and released quickly and utilizes a pneumatic release mechanism to free the pallet. The pallet comprises two plates screwed together with the lower plate having lugs and slots that cooperate with recesses and a pin in the pallet arm to locate the pallet. Although these quick release arrangements are an improvement they do have short comings in terms of convenience and operator simplicity. Also they all involve additional manufacturing steps in preparing the pallets.